ABSTRACT
Prevention of oil spill is one of the important issues from the view point of conservation of maritime environment. A double-hull system is effective to reduce risk of oil spill from tankers. However it is important to further reduce risk of oil spill considering oil spill accidents from double-hull tankers such as Baltic Carrier in 2001. In the present study a series of large-scale non-linear finite element simulation is carried out assuming that VLCC run aground with rigid rock from top of the bow where global ship motion is considered with introducing static fluid pressure. Crushing and fracture of double bottom structure is investigated with changing speed of the ship. Energy absorption of bottom structural members such as shell, longitudinal, floor and collision bulkhead are compared and discussed. In the present study, “critical grounding velocity” is newly defined and simplified method to estimate the critical grounding velocity is proposed, and results estimated by simplified method are compared with that estimated by numerical simulation. Recently highly ductile steel (HDS) was developed where elongation is much higher than those of conventional steels while keeping other material characteristics such as yield and tensile strength as well as workability (i.e., weldability). The scope of the present project introducing HDS to ship bottom structure is shortly explained.
